If a valid certificate is installed on your domain than it shall redirect it to the https protocol. To make your WordPress installation redirect to the https protocol you can do the following:

1. Change the protocol from your wp-admin page from the WordPress Admin Panel -> Settings -> General and change the protocols in "WordPress Address (URL)" and "Site Address (URL)"
https://prnt.sc/gk3tjl

2. Now change the protocol in Webuzo to update the WordPress records in your panel from the Edit Installation Page of your installation and change the "URL" variable from http to https. You can refer to our guide here for more details on how to edit the installation:
http://softaculous.com/docs/How_to_edit_an_installation

Hope this helps you.

Please let us know if you need any further information. We will be happy to help you.

Also to check why your domain is not being shown in the Lets Encrypt drop down menu, can you please open a support ticket here with your server root details and we shall look into the same:
https://www.softaculous.com/support/

Thanks for your previous response. Your response was helpful, though it is frustrating the procedure for setting up a website that is migrated from another already-operating word press install. It add unnecessary contortions that first a valid certificate must be installed before 443 can be used.

And worse, I have a fresh install of webuzo, and the Let's Encrypt is not showing the option to issue a certificate for the domains. So now I am stuck.